(a) Technical Field
The present invention relates to a mass damper which reduces a resonant phenomenon of a vehicle; and more particularly, to a compression-type mass damper which is fixed to an outer surface of a target in a pressing manner, and a suspension system and a vehicle using the same.
(b) Description of the Related Art
Generally, NVH (noise, vibration, harshness) of vehicles are factors which must be reduced so as to meet governmental regulations, such as the following European regulations (with decibel levels indicated): EU#1 (92 dB), EU#9 (81 dB), and EU#6 (78 dB).
As an example of efforts for reducing NVH, there is a method in which a mass damper formed by coupling a mass made of rubber or urethane with a bracket is mounted to a drive system, a vehicle body connection part, or an exhaust system.
For example, in a method of mounting the mass damper to the drive system, the mass damper is mounted on an axle housing, so that the magnitude of vibration of the axle can be reduced by vibration absorption of the mass damper. In a method of mounting the mass damper to the vehicle body connection part, the mass damper is mounted on the junction between a chassis and a vehicle body, so that the magnitude of vibration of the vehicle body can be reduced by vibration absorption of the mass damper. In a method of mounting the mass damper to the exhaust system, the mass damper is mounted on an exhaust pipe, so that the magnitude of vibration of the exhaust pipe can be reduced by vibration absorption of the mass damper.
As such, use of the mass damper which is mounted on a vibration source or a vibration transfer path assists in reducing NVH to meet the European regulations such as EU#1 (92 dB), EU#9 (81 dB), and EU#6 (78 dB).
However, NVH is characterized in that it is exacerbated by a resonance phenomenon of a vibration source derived from a road and a vibration source derived from the engine/drive system. In particular, a suspension system is a basic structure for coupling the vehicle body with the chassis and acts as a path through which vibration amplified by resonance is transmitted. Therefore, it is difficult to meet the European regulation, such as EU#1 (92 dB), EU#9 (81 dB), and EU#6 (78 dB) only using the mass damper.
Further, the suspension system employs a bushing similar to the mass damper so as to adjust the stiffness of the junction between the vehicle body and a suspension component and thus reduce vibration, but it is ineffective in avoiding influence of a resonant frequency of vibration transmitted from the road or influence of a resonant frequency of vibration generated from the engine/drive system and transmitted to the vehicle body.